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<TITLE>[Chapter 1] 1.8 The java.util.zip Package</TITLE>
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<h2 CLASS=sect1><A CLASS="TITLE" NAME="JFC-CH-1-SECT-8">1.8 The java.util.zip Package</A></h2>

<P CLASS=para>
The <tt CLASS=literal>java.util.zip</tt> package is new in Java 1.1.
It contains classes that provide support for general-purpose
data compression and decompression using the ZLIB compression
algorithms. The important classes in
<tt CLASS=literal>java.util.zip</tt> are those that provide the means
to read and write data that is compatible with the popular 
GZIP and ZIP formats: <tt CLASS=literal>GZIPInputStream</tt>,
<tt CLASS=literal>GZIPOutputStream</tt>, <tt CLASS=literal>ZipInputStream</tt>,
and <tt CLASS=literal>ZipOutputStream</tt>.

<P CLASS=para>
The GZIP and ZIP classes are easy to use because they
subclass <tt CLASS=literal>java.io.
FilterInputStream</tt> and 
<tt CLASS=literal>java.io.FilterOutputStream</tt>. While
a GZIP file is simply a stream of compressed data, a ZIP
file, or archive, can contain multiple compressed files.
A <tt CLASS=literal>ZipEntry</tt> 
object represents each compressed file in the archive. 
The <tt CLASS=literal>ZipFile</tt>
class is provided as a convenience for reading an archive; it allows
nonsequential access to the entries in a ZIP file while
the <tt CLASS=literal>ZipInputStream</tt> class provides only sequential
access.

<P CLASS=para>
The remainder of the classes in <tt CLASS=literal>java.util.zip</tt> 
support the GZIP and ZIP classes. 
The generic <tt CLASS=literal>Deflater</tt> and <tt CLASS=literal>Inflater</tt> 
classes implement the ZLIB algorithms; they are used by 
<tt CLASS=literal>DeflaterOutputStream</tt> and 
<tt CLASS=literal>InflaterInputStream</tt> to 
decompress and compress data. The <tt CLASS=literal>Checksum</tt> 
interface and the classes that implement it, <tt CLASS=literal>Adler32</tt> 
and <tt CLASS=literal>CRC32</tt>, define algorithms that generate 
checksums from stream data. These checksums
are used by the <tt CLASS=literal>CheckedInputStream</tt> and 
<tt CLASS=literal>CheckedOutputStream</tt> classes.

<P CLASS=para>
See <A HREF="ch18_01.htm">Chapter 18, <i>The java.util.zip Package</i></A>, for complete reference material on all of the
classes in the <tt CLASS=literal>java.util.zip</tt> package.

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